“That’s why we went out there, to save anybody,” volunteer Cade Till told KTRK. But after seeing the debris, Till realized the likelihood was slim.

The 767 was in a normal descent as it approached the airport, then went into a “very, very rapid descent” at 6,300 feet, National Transportation Safety Board Chairman Robert Sumwalt told reporters.

Atlas Air said its priority is the three people on the plane and their family members. The operator said it was cooperating with federal investigators.

The president of the Airline Professionals Association, Teamsters Local 1224, said the three people on the flight were union members.

“Our union stands together as a family and in support of our members’ families,” said Daniel C. Wells, who is also an Atlas Air captain. “Our focus is on our friends and colleagues who were on that plane, and we are doing everything we can to support their families.”

The plane was built in 1992

Aerial images from CNN affiliate KPRC showed emergency responders on airboats near the site of a significant amount of debris.

“The joint operation between the Chambers County Sheriff’s Office, the National Transportation Safety Board and the FBI will continue to attempt recovery of victims and the aircraft,” the sheriff’s office said in a statement.

The plane was located in Jack’s Pocket at the north end of Trinity Bay, the Chambers County Sheriff’s Office said on Facebook.

According to the FAA website, the plane was built in 1992 and the flight number was 3591.

Boeing said it was saddened to hear about the crash.

“We are concerned about the safety of the three people reported to be on board the airplane,” it said. “We are prepared to provide technical assistance to the National Transportation Safety Board as it investigates the accident.”